The invention relates to a hydraulic switching assembly for a motor vehicle, comprising a hydraulic pump that feeds a hydraulic medium from a sump via hydraulic lines and at least via a magnetic valve assembly with a magnetically actuatable switching valve to a switching element, in order to hydraulically actuate the switching element between two switching positions.
In particular, the invention extends to a hydraulic switching assembly in motor applications of motor vehicles, wherein motor oil from an oil sump of the motor is provided as the hydraulic medium.
In general, switching valves are known that are used for controlling two-stage switchable motor elements. Here, an existing oil pressure in the motor oil circuit is used to actuate the locking mechanism of the switchable motor elements preferably by a 3/2-way directional control switching valve. The directional control switching valve is controlled corresponding to an engine characteristic map stored in the engine control module as a function of various parameters, such as engine speed, engine load, vehicle speed, operating temperature, etc. As a rule, the switching valve is mounted directly in the cylinder head and integrated in the oil circuit, wherein the switching valve includes an electromagnet and a hydraulic part. When the switching valve is energized, oil flows from the oil pump to the switchable motor elements and switches the locking mechanisms of the switchable motor elements. When the switching valve is not energized, the passage from the oil pump to the switching elements is closed and the oil flows via a bypass through the switching gallery with low pressure back to the oil pan, wherein the locking mechanisms are switched back into their original position. The switching times depend on the mechanics of the switching valve and on the design of the hydraulic circuit.
A disadvantage is that, when the engine is at a standstill, the oil pressure in the motor circuit decreases, so that the switchable motor elements are no longer controllable. Furthermore, the system has a high sensitivity with respect to oil pressure fluctuations.